Structural and Componential Engineering of Co2P&CoP@N–C Nanoarrays for Energy-Efficient Hydrogen Production from Water Electrolysis

The development of electrocatalysts for efficient water splitting is a pivotal and challenging task. Transition-metal phosphides (TMPs) have been known as one of the most promising candidates for the efficient hydrogen evolution reaction (HER) due to their favorable intrinsic reactivity. However, structural engineering related to the gas bubbles evolution and tiny regulation of components concerned with the electronic structure remained as a significant challenge that requires further optimization. Herein, the nanoarrays (NAs) composed of ultrasmall Co2P and CoP nanoparticle-embedded N-doped carbon matrix (Co2P&CoP@N-C) are prepared and demonstrated an overpotential of 62.8 ± 4.7 mV at 10 mA cm-2 in 1.0 M KOH. The nanoarray-structured electrocatalyst revealed the superaerophobicity and facilitates the detachment of the in situ formed hydrogen gas bubbles, ensuring abundant catalytic sites and electrode-electrolyte interface for the mass transfer process. The amount of P doping modulated the local electron density around Co and P atoms, which attains a favorable compromise to afford sufficient electrons for the electrocatalysis and inhibit the negative influence of H2 desorption. Significantly, the lowered overpotential induced by the electrocatalyst surface architecture is much stronger than that of the component content and promotes the electrocatalytic activity.